The present invention relates to substituted monocyclopentadienyl, monoindenyl, monofluorenyl and heterocyclopentadienyl complexes of chromium, molybdenum or tungsten in which at least one of the substituents on the cyclopentadienyl ring carries a donor function which is bonded rigidly, not exclusively via sp3-hybridized carbon or silicon atoms, and to a process for the polymerization of olefins.
Many of the catalysts used for the polymerization of xcex1-olefins are based on immobilized chromium oxides (see, for example, Kirk-Othmer, xe2x80x9cEncyclopedia of Chemical Technologyxe2x80x9d, 1981, Vol.16, p. 402). These generally give ethylene hompolymers and copolymers of high molecular weights, but are relatively insensitive to hydrogen and thus do not allow simple control of the molecular weight. By contrast, use of bis(cyclopentadienyl)chromium (U.S. Pat. No. 3,709,853), bis(indenyl)chromium or bis(fluorenyl)chromium (U.S. Pat. No. 4,015,059) applied to an inorganic, oxidic support allows simple control of the molecular weight of polyethylene by addition of hydrogen.
As in Ziegler-Natta systems, there has recently also been interest in finding chromium catalyst systems having a uniformly defined active center, so-called single-site catalysts. By targeted variation of the ligand structure, the aim is to be able to modify in a simple manner the activity and copolymerization behavior of the catalyst and the properties of the resultant polymers.
Thus, EP-A-742046 discloses so-called constrained geometry complexes of the group 6, a special process for their preparation (via metal tetraamides), and a process for the preparation of a polyolefin in the presence of such catalysts. The ligand structure consists of an anionic donor which is linked to a cyclopentadienyl radical.
K. H. Theopold et al. in Organomet. 1996, 15, 5284-5286, have described an analogous {[(tert-butylamido)dimethylsilyl]-(tetramethylcyclopentadienyl)} chromium chloride complex for the polymerization of olefins. This complex selectively polymerizes ethylene. It is not possible either to incorporate comonomers, for example hexene, nor to polymerize propene.
This disadvantage can be overcome by using structurally very similar systems. For example, DE-A1-19710615 describes monocyclopentadienylchromium compounds substituted by donor ligands which can be used, for example, to polymerize propene as well. The donor in these compounds is from the 15th group of the Periodic Table of the Elements and is neutral. The donor is bonded to the cyclopentadienyl ring via a (ZR2)n fragment, where R is hydrogen, alkyl or aryl, Z is an atom from the 14th group of the Periodic Table of the Elements, and n is 1. DE-A1-19630580 states that the combination of Z=carbon with an amine donor gives good results.
WO-A-96/13529 describes reduced transition-metal complexes from Groups 4 to 6 of the Periodic Table of the Elements with polydentate monoanionic ligands. These include, inter alia, cyclopentadienyl ligands, preferably containing a donor function bonded via a (CR2)p bridge, where R is hydrogen or a hydrocarbyl radical having 1 to 20 carbon atoms, and p is 1 to 4. The preferred transition metal is titanium.
There are also ligand systems in which the donor group is linked rigidly to the cyclopentadienyl radical. Such ligand systems and their metal complexes are reviewed, for example, by P. Jutzi and U. Siemeling in J. Organomet. Chem. (1995), 500, 175-185, Section 3. M. Enders et. al., in Chem. Ber. (1996), 129, 459-463, describe 8-quinolyl-substituted cyclopentadienyl ligands and their titanium and zirconium trichloride complexes. 2-Picolylcyclopentadienyltitanium trichloride in combination with methylaluminoxane has been used by M. Blais, J. Chien and M. Rausch in Organomet. (1998), 17 (17) 3775-3783 for the polymerization of olefins.
It is an object of the present invention to find novel catalyst systems which can easily be modified and are suitable for the polymerization of xcex1-olefins.
We have found that this object is achieved by substituted monocyclopentadienyl, monoindenyl, monofluorenyl and heterocyclopentadienyl complexes of chromium, molybdenum or tungsten in which at least one of the substituents on the cyclopentadienyl ring carries a donor function which is bonded rigidly, not exclusively via sp3-hybridized carbon or silicon atoms.
We have furthermore found a process for the polymerization or copolymerization of olefins in which olefins are polymerized in the presence of the following components:
(A) a substituted monocyclopentadienyl, monoindenyl, monofluorenyl or heterocyclopentadienyl complex as claimed in claim 1, of the formula I
[Yxe2x80x94Mxe2x80x94Xn]mxe2x80x83xe2x80x83I,
where;
M is chromium, molybdenum or tungsten
Y is described by the formula II 
where:
E1-E5 are carbon or a maximum of one E1 to E5 is phosphorus or nitrogen,
Z is NR5R6, PR5R6, OR5, SR5 or an unsubstituted, substituted or fused, partially unsaturated heterocyclic or heteroaromatic ring system,
B is one of the following groups: 
xe2x80x83and in addition, if Z is an unsubstituted, substituted or fused, partially unsaturated heterocyclic or heteroaromatic ring system, may alternatively be 
where
L1 and L2are silicon or carbon,
k is 1, and is alternatively 0 if Z is an unsubstituted, substituted or fused, partially unsaturated heterocyclic or heteroaromatic ring system,
X independently of one another, are fluorine, chlorine, bromine, iodine, hydrogen, C1-C10-alkyl, C2-C10-alkenyl, C6-C20-aryl, alkylaryl having 1-10 carbon atoms in the alkyl radical and 6-20 carbon atoms in the aryl radical, NR15R16, OR15, SR15, SO3R15, OC(O)R15, CN, SCN, xcex2-diketonate, CO, BF4xe2x88x92, PF6xe2x88x92, or a bulky, non-coordinating anion,
R1-R16 independently of one another, are hydrogen, C1-C20-alkyl, C2-C20-alkenyl, C6-C20-aryl, alkylaryl having 1 to 10 carbon atoms in the alkyl radical and 6-20 carbon atoms in the aryl radical, or SiR173, where the organic radicals R1-R16 may also be substituted by halogens, and in each case two geminal or vicinal radicals R1-R16 may also be linked to form a five- or six-membered ring,
R17 independently of one another, are hydrogen, C1-C20-alkyl, C2-C20-alkenyl, C6-C20-aryl, alkylaryl having 1 to 10 carbon atoms in the alkyl radical and 6-20 carbon atoms in the aryl radical, and in each case two geminal radicals R17 may also be linked to form a five- or six-membered ring,
n is 1, 2 or 3, and
m is 1, 2 or 3,
(B) if desired, one or more activator compounds, and
(C) if desired, one or more additional conventional olefin-polymerization catalysts.
We have furthermore found olefin polymers obtainable by the process according to the invention, and fibers, films and moldings which comprise the olefin polymers according to the invention.
In order to make the bonding to the cyclopentadienyl ring rigid, the most direct link to the donor function contains at least one sp- or sp2-hybridized carbon atom, preferably at least one to three sp2-hybridized carbon atoms. The direct link preferably contains an unsaturated double bond or an aromatic ring or forms with the donor a partially unsaturated or aromatic heterocyclic system.
The cyclopentadienyl ring is 5 bonded to the metal center, preferably chromium, in the complexes according to the invention and can also be a heterocyclopentadienyl ligand, i.e. the at least one carbon atom may also be replaced by a heteroatom from Group 15 or 16. In this case, a C5 ring carbon atom is preferably replaced by phosphorus. In particular, the cyclopentadienyl ring is substituted by further alkyl groups, which can also form a five- or six-membered ring, for example tetrahydroindenyl, indenyl, benzindenyl or fluorenyl.
The donor is a neutral functional group containing an element from the 15th or 16th group of the Periodic Table of the Elements, for example amine, imine, carboxamide, carboxylate, ketone (oxo), ether, thioketone, phosphine, phosphite, phosphine oxide, sulfonyl or sulfonamide, or an unsubstituted, substituted or fused, partially unsaturated heterocyclic or heteroaromatic ring system.
Preference is given to substituted monocyclopentadienyl, monoindenyl, monofluorenyl and heterocyclopentadienyl complexes of the formula I
[Yxe2x80x94Mxe2x80x94Xn]mxe2x80x83xe2x80x83I,
where:
M is chromium, molybdenum or tungsten
Y is described by the formula II 
where:
E1-E5 are carbon or a maximum of one E1 to E5 is phosphorus or nitrogen,
Z is NR5SR6, PR5R6, OR5, SR5 or an unsubstituted, substituted or fused, partially unsaturated heterocyclic or heteroaromatic ring system,
B is one of the following groups: 
xe2x80x83and in addition, if Z is an unsubstituted, substituted or fused, partially unsaturated heterocyclic or heteroaromatic ring system, may alternatively be 
where
L1, and L2are silicon or carbon,
k is 1, and is alternatively 0 if Z is an unsubstituted, substituted or fused, partially unsaturated heterocyclic or heteroaromatic ring system,
X independently of one another, are fluorine, chlorine, bromine, iodine, hydrogen, C1-C10-alkyl, C2-C10-alkenyl, C6-C20-aryl, alkylaryl having 1-10 carbon atoms in the alkyl radical and 6-20 carbon atoms in the aryl radical, NR15R16, OR15, SR15, SO3R15, OC(O)R15, CN, SCN, xcex2-diketonate, CO, BF4xe2x88x92, PF6xe2x88x92, or bulky, non-coordinating anions,
R1-R16 independently of one another, are hydrogen, C1-C20-alkyl, C2-C20-alkenyl, C6-C20-aryl, alkylaryl having 1 to 10 carbon atoms in the alkyl radical and 6-20 carbon atoms in the aryl radical, or SiR173, where the organic radicals R1-R16 may also be substituted by halogens, and in each case two geminal or vicinal radicals R1-R16 may also be linked to form a five- or six-membered ring,
R17 independently of one another, are hydrogen, C1-C20-alkyl, C2-C20-alkenyl, C6-C20-aryl, alkylaryl having 1 to 10 carbon atoms in the alkyl radical and 6-20 carbon atoms in the aryl radical, and in each case two geminal radicals R17 may also be linked to form a five- or six-membered ring,
n is 1, 2 or 3, and
m is 1, 2 or 3.
A particularly suitable transition metal M is chromium.
Y is a substituted cyclopentadienyl system, where the radical xe2x80x94Bxxe2x80x94Z carries a rigidly bonded donor function. The cyclopentadienyl ring is bonded to the transition metal via an xcex75-bond. The donor can be bonded coordinatively or non-coordinatively. The donor is preferably coordinated intramolecularly to the metal center.
E1 to E5 are preferably four carbon atoms and one phosphorus atom or only carbon atoms, and very particularly preferably all of E1 to E5 are carbon.
Z can, for example, form an amine, ether, thioether or phosphine together with the bridge B. However, Z can also be an unsubstituted, substituted or fused, heterocyclic aromatic ring system, which, besides carbon ring members, may also contain heteroatoms from the group consisting of oxygen, sulfur, nitrogen and phosphorus. Examples of 5-membered heteroaryl ring groups, which, besides carbon atoms, may also contain one to four nitrogen atoms or one to three nitrogen atoms and/or one sulfur or oxygen atom as ring members, are 2-furyl, 2-thienyl, 2-pyrrolyl, 3-isoxazolyl, 5-isoxazolyl, 3-isothiazolyl, 5-isothiazolyl, 1-pyrazolyl, 3-pyrazolyl, 5-pyrazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl, 1,2,4-oxadiazol-3-yl, 1,2,4-oxadiazol-5-yl, 1,3,4-oxadiazol-2-yl or 1,2,4-triazol-3-yl. Examples of 6-membered heteroaryl groups, which may contain one to four nitrogen atoms and/or one phosphorus atom, are 2-pyridinyl, 2-phosphabenzolyl, 3-pyridazinyl, 2-pyrimidinyl, 4-pyrimidinyl, 2-pyrazinyl, 1,3,5-triazin-2-yl and 1,2,4-triazin-3-yl, 1,2,4-triazin-5-yl or 1,2,4-triazin-6-yl. The 5- and 6-membered heteroaryl ring groups here may also be substituted by C1-C10-alkyl, C6-C10-aryl, alkylaryl having 1 to 10 carbon atoms in the alkyl radical and 6-10 carbon atoms in the aryl radical, trialkylsilyl or halogens, such as fluorine, chlorine or bromine, or may be fused to one or more aromatic or heteroaromatic ring systems. Examples of benzo-fused 5-membered heteroaryl groups are 2-indolyl, 7-indolyl, 2-cumaronyl, 7-cumaronyl, 2-thionaphthenyl, 7-thionaphthenyl, 3-indazolyl, 7-indazolyl, 2-benzimidazolyl and 7-benzimidazolyl. Examples of benzo-fused 6-membered heteroaryl groups are 2-quinolyl, 8-quinolyl, 3-cinnolyl, 8-cinnolyl, 1-phthalazyl, 2-quinazolyl, 4-quinazolyl, 8-quinazolyl, 5-quinoxalyl, 4-acridyl, 1-phenanthridyl and 1-phenazyl. The naming and numbering of the heterocyclic systems has been taken from L. Fieser and M. Fieser, Lehrbuch der organischen Chemie [Textbook of Organic Chemistry], 3rd revised edition, Verlag Chemie, Weinheim 1957. In a preferred embodiment, Z is an unsubstituted, substituted or fused, heteroaromatic ring system or NR5R6. Preference is given here to simple systems which are readily accessible and inexpensive and are selected from the following group: 
A suitable choice of the radicals R18 to R27 allows the activity of the catalyst and the molecular weight of the resultant polymer to be influenced. Suitable substituents R18 to R27 are the same radicals as described for R1-R16 and halogens, for example fluorine, chlorine or bromine, where, if desired, it is also possible for two vicinal radicals R18 to R27 to be linked to form a 5- or 6-membered ring and also to be substituted by halogens, such as fluorine, chlorine or bromine. Preferred radicals R18 to R27 are hydrogen, methyl, ethyl, n-propyl, n-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, vinyl, allyl, benzyl, phenyl, naphthyl, biphenyl and anthranyl, and fluorine, chlorine and bromine. Suitable organosilicon substituents are, in particular, trialkylsilyl groups having 1 to 10 carbon atoms in the alkyl radical, in particular trimethylsilyl groups. Z is very particularly preferably an unsubstituted or substituted, for example alkyl-substituted, in particular 8-linked quinolyl, for example 8-quinolyl, 8-(2-methylquinolyl), 8-(2,3,4-trimethylquinolyl) or 8-(2,3,4,5,6,7-hexamethylquinolyl). These are very simple to prepare and simultaneously give very good activities.
The rigid bridge B between the cyclopentadienyl ring and the functional group Z is a divalent organic radical consisting of carbon and/or silicon units with a chain length of 1 to 3. The activity of the catalyst can be modified by changing the link length between the cyclopentadienyl ring and the heteroatom donor. Since the nature of Z is also affected by the number of bridging atoms between the cyclopentadienyl radical and the heteroatom, a variety of combinations of B with Z can be chosen here to exert an influence. B can be bonded to Z via L1 or CR9. Owing to the ease of preparation, the combination of B as CHxe2x95x90CH or 1,2-phenylene with Z as NR5R6 and also of B as CH2, C(CH3)2 or Si(CH3)2 and Z as unsubstituted or substituted 8-quinolyl or unsubstituted or substituted 2-pyridyl is preferred. Systems without a bridge B, in which k is 0, are also very particularly simple to prepare. In this case, Z is preferably unsubstituted or substituted quinolyl, in particular 8-quinolyl.
Various properties of the catalyst system can also be modified by varying the substituents R1-R16. The accessibility of the metal atom M to the olefins to be polymerized can be modified through the number and type of the substituents, in particular of R1-R4. Thus, it is possible to modify the activity and selectivity of the catalyst with respect to various monomers, in particular sterically hindered monomers. Since the substituents can also affect the rate of termination reactions of the growing polymer chain, this is also a way of modifying the molecular weight of the resultant polymers. The chemical structure of the substituents R1 to R16 can therefore be varied within broad ranges in order to achieve the desired results and to obtain a customized catalyst system. Examples of suitable C-organic substituents R1-R16 are the following: C1-C20-alkyl, where the alkyl may be linear or branched, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl and n-dodecyl, 5- to 7-membered cycloalkyl, which may itself carry a C6-C10-aryl group as substituent, for example cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane and cyclododecane, C2-C20-alkenyl, where the alkenyl may be linear, cyclic or branched and the double bond may be internal or terminal, for example vinyl, 1-allyl, 2-allyl, 3-allyl, butenyl, pentenyl, hexenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl and cyclooctadienyl, C6-C20-aryl, where the aryl radical may be substituted by further alkyl groups, for example phenyl, naphthyl, biphenylyl, anthranyl, o-, m-, p-methylphenyl, 2,3-, 2,4-, 2,5- or 2,6-dimethylphenyl, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6- and 3,4,5-trimethylphenyl, and arylalkyl, where the arylalkyl may be substituted by further alkyl groups, for example benzyl, o-, m- and p-methylbenzyl, 1- and 2-ethylphenyl, where, if desired, two of R1 to R16 may also be linked to form a 5- or 6-membered ring, and the organic radicals R1-R16 may also be substituted by halogens, for example fluorine, chlorine or bromine. In organosilicon substituents SiR173, suitable radicals for R17 are the same ones as listed in detail above for R1-R16, where, if desired, it is also possible for two R17 radicals to be linked to form a 5- or 6-membered ring, for example trimethylsilyl, triethylsilyl, butyldimethylsilyl, tributylsilyl, triallylsilyl, triphenylsilyl and dimethylphenylsilyl. Preferred radicals R5-R16 are hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, vinyl, allyl, benzyl, phenyl, orthodialkyl- and -dichloro-substituted phenyls, trialkyl- and trichloro-substituted phenyls, naphthyl, biphenyl and anthranyl Particularly suitable organosilicon substituents are trialkylsilyl groups having 1 to 10 carbon atoms in the alkyl radical, in particular trimethylsilyl groups. Particularly preferred radicals R5 and R6 are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, allyl, benzyl, phenyl and trialkylsilyl groups. R1 to R4 are preferably hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, benzyl and phenyl. In preferred transition-metal complexes, E1E2E3E4E5 together with R1R2R3R4 is a monoalkylcyclopentadienyl radical, for example 3-methylcyclopentadienyl, 3-ethylcyclopentadienyl, 3-isopropylcyclopentadienyl or 3-tert-butylcyclopentadienyl, a dialkylcyclopentadienyl radical, for example tetrahydroindenyl, 2,4-dimethylcyclopentadienyl or 3-methyl-5-tert-butylcyclopentadienyl, a trialkylcyclopentadienyl radical, for example 2,3,5-trimethylcyclopentadienyl, or a tetraalkylcyclopentadienyl radical, for example 2,3,4,5-tetramethylcyclopentadienyl. Furthermore, preference is also given to compounds in which two vicinal R1 to R4 radicals form a fused six-membered ring system, in which E1E2E3E4E5 together with R1R2R3R4 is unsubstituted or substituted indenyl, for example indenyl, 2-methylindenyl, 2-ethylindenyl, 2-isopropylindenyl, 3-methylindenyl, 4-phenylindenyl, 2-methyl-4-phenylindenyl or 4-naphthylindenyl, or a benzindenyl system, for example benzindenyl or 2-methylbenzindenyl. In very particularly preferred transition-metal complexes, E1E2E3E4E5 together with R1R2R3R4 is indenyl.
As in the metallocenes, the transition-metal complexes may be chiral. Thus, on the one hand, the cyclopentadienyl radical can have one or more centers of chirality, or alternatively the cyclopentadienyl system may itself only be enantiotropic, so that the chirality is only induced by bonding thereof to the transition metal M This can be effected, for example, simply through two different substituents (the donor substituent and, for example, an alkyl radical) on the cyclopentadienyl ring in order to give R- and S-enantiomers of the transition-metal complexes (for the formalism of chirality in cyclopentadienyl compounds, see R. Halterman, Chem. Rev. 92, (1992), 965-994).
The substituents X arise, for example, through the choice of the corresponding metal starting compounds used for the synthesis of the metal complexes, but can also be varied subsequently. Particularly suitable substituents X are the halogens, such as fluorine, chlorine, bromine and iodine, especially chlorine. Simple alkyl radicals, such as methyl, ethyl, propyl, butyl, vinyl, allyl, phenyl and benzyl, also represent advantageous ligands X. Further ligands X which may be mentioned, merely by way of example and in no way to be taken as limiting, are trifluoroacetate, BF4xe2x88x92, PF6xe2x88x92 and weakly or non-coordinating anions (see, for example, S. Strauss in Chem. Rev 1993, 93, 927-942), such as B(C6F5)4xe2x88x92. The designation of the ligands X as anions does not stipulate the type of bonding to the transition metal M. For example, if X is a non- or weakly coordinating anion, the interaction between the metal M and the ligand X is of a rather more electrostatic nature. The various types of bonding are known to the person skilled in the art.
Amides, alkoxides, sulfonates, carboxylates and xcex2-diketonates are also particularly suitable. By varying the radicals R15 and R16, it is possible, for example, to finely adjust physical properties, such as solubility. The radicals R15 and R16 are preferably C1-C10-alkyl, such as methyl, ethyl, n-propyl, n-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl and n-octyl and vinyl, allyl, benzyl and phenyl. Some of these substituted ligands X are very particularly preferred, since they are obtainable from inexpensive and readily accessible starting materials. Thus, a particularly preferred embodiment is for X to be dimethylamide, methoxide, ethoxide, isopropoxide, phenoxide, naphthoxide, triflate, p-toluenesulfonate, acetate or acetylacetonate.
The number n of ligands X depends on the oxidation state of the transition metal M. The number n can thus not be given in general terms. The oxidation state of the transition metals M in catalytically active complexes is usually known to the person skilled in the art. Chromium, molybdenum and tungsten are very probably in the +3 oxidation state. However, it is also possible to employ complexes whose oxidation state does not correspond to that of the active catalyst. Such complexes can then be correspondingly reduced or oxidized by suitable activators. Preference is given to chromium complexes in the +3 oxidation state.
The donor Z can be coordinatively bonded to the transition metal M. This is possible intermolecularly or intramolecularly. The donor Z is preferably coordinatively bonded to M intramomlecularly. However, this may change during the polymerization.
The transition-metal complex of the formula I can be in the form of a monomeric, dimeric or trimeric compound, where m is 1, 2 or 3 respectively. It is possible here, for example, for one or more ligands X to bridge two metal centers M.
Preferred complexes are, for example, 1-(8-quinolyl)-2-methyl-4-methylcyclopentadienylchromium(III) dichloride, 1-(8-quinolyl)-3-isopropyl-5-methylcyclopentadienylchromium(III) dichloride, 1-(8-quinolyl)-3-tert-butyl-5-methylcyclopentadienylchromium(III) dichloride, 1-(8-quinolyl)-2,3,4,5-tetramethylcyclopentadienylchromium(III) dichloride, 1-(8-quinolyl)tetrahydroindenylchromium(III) dichloride, 1-(8-quinolyl)indenylchromium(III) dichloride, 1-(8-quinolyl)-2-methylindenylchromium(III) dichloride, 1-(8-quinolyl)-2-isopropylindenylchromium(III) dichloride, 1-(8-quinolyl)-2-ethylindenylchromium(III) dichloride, 1-(8-quinolyl)-2-tert-butylindenylchromium(III) dichloride, 1-(8-quinolyl)benzindenylchromium(III) dichloride, 1-(8-quinolyl)-2-methylbenzindenylchromium(III) dichloride, 1-(8-(2-methylquinolyl))-2-methyl-4-methylcyclopentadienylchromium(III) dichloride, 1-(8-(2-methylquinolyl))-2,3,4,5-tetramethylcyclopentadienylchromium(III) dichloride, 1(8-(2-methylquinolyl))tetrahydroindenylchromium(III) dichloride, 1-(8-(2-methylquinolyl))indenylchromium(III) dichloride, 1-(8-(2-methylquinolyl))-2-methylindenylchromium(III) dichloride, 1-(8-(2-methylquinolyl))-2-isopropylindenylchromium(III) dichloride, 1-(8-(2-methylquinolyl))-2-ethylindenylchromium(III) dichloride, 1-(8-(2-methylquinolyl))-2-tert-butylindenylchromium(III) dichloride, 1-(8-(2-methylquinolyl))-benzindenylchromium(III) dichloride and 1(8-(2-methylquinolyl))-2-methylbenzindenylchromium(III)dichloride.
The preparation of functional cyclopentadienyl ligands has been known for some time. Various synthetic routes for these complex ligands are described, for example, by M. Enders et. al. in Chem. Ber. (1996), 129, 459-463 or P. Jutzi and U. Siemeling in J. Orgmet. Chem. (1995), 500, 175-185.
The metal complexes, in particular the chromium complexes, can be obtained in a simple manner if the corresponding metal salts, for example metal chlorides, are reacted with the ligand anion (for example analogously to the examples in DE 19710615).
The olefin polymerization process according to the invention can be combined with all industrially known polymerization processes at temperatures in the range from 20 to 300xc2x0 C. and under pressures of from 5 to 4000 bar. The advantageous pressure and temperature ranges for carrying out the process are accordingly highly dependent on the polymerization method. Thus, the catalyst systems used in accordance with the invention can be employed in all known polymerization processes, i.e., for example, in high-pressure polymerization processes in tubular reactors or autoclaves, in suspension polymerization processes, in solution polymerization processes or in gas-phase polymerization. In the high-pressure polymerization processes, which are usually carried out at pressures of from 1000 to 4000 bar, in particular from 2000 to 3500 bar, high polymerization temperatures are generally also used. Advantageous temperature ranges for these high-pressure polymerization processes are from 200 to 280xc2x0 C., in particular from 220 to 270xc2x0 C. In low-pressure polymerization processes, a temperature which is at least a few degrees below the softening point of the polymer is generally used. In particular, temperatures of from 50 to 180xc2x0 C., preferably from 70 to 120xc2x0 C., are used in these polymerization processes. In suspension polymerizations, the polymerization is usually carried out in a suspension medium, preferably in an alkane. The polymerization temperatures are generally in the range from xe2x88x9220 to 115xc2x0 C., and the pressure is generally in the range from 1 to 100 bar. The solids content of the suspension is generally in the range from 10 to 80%. The polymerization can be carried out batchwise, for example in stirred autoclaves, or continuously, for example in tubular reactors, preferably in loop reactors. In particular, the Phillips-PF process, as described in U.S. Pat. No. 3,242,150 and U.S. Pat. No. 3,248,179, can be used. Of said polymerization processes, gas-phase polymerization, in particular in gas-phase fluidized-bed reactors, solution polymerization, and suspension polymerization, in particular in loop and stirred-tank reactors, are particularly preferred in accordance with the invention. The gas-phase polymerization can also be carried out by the so-called condensed, supercondensed or supercritical method. Different or even the same polymerization processes can also, if desired, be connected in series with one another, forming a polymerization cascade. Furthermore, an additive, for example hydrogen, can be used in the polymerization processes in order to regulate the polymer properties.
The process according to the invention can be used for the polymerization of various olefinically unsaturated compounds, where the term polymerization also includes copolymerization. In contrast to some known iron and cobalt complexes, the transition-metal complexes employed in accordance with the invention have good polymerization activity, even with higher xcex1-olefins, and consequently their suitability for copolymerization should be particularly emphasized. Suitable olefins here, besides ethylene and xcex1-olefins having 3 to 12 carbon atoms, for example propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and 1-dodecene, are also internal olefins and non-conjugated and conjugated dienes, such as butadiene, 1,5-hexadiene and 1,6-heptadiene, cyclic olefins, such as cyclohexene, cyclopentene and norbornene, and polar monomers, such as acrylates, acrolein, acrylonitrile, vinyl ethers, allyl ethers and vinyl acetate. Vinylaromatic compounds, such as styrene, can also be polymerized by the process according to the invention. Preferably, at least one olefin selected from the group consisting of ethene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and 1-decene is polymerized. In a preferred embodiment of the process according to the invention, the monomers used are mixtures of ethylene with C3- to C12-xcex1-olefins. In contrast to the situation with some iron and cobalt compounds, higher xcex1-olefins can also be polymerized very well using the catalyst system according to the invention. In a further preferred embodiment of the process according to the invention, an olefin selected from the group consisting of propene, 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene is polymerized. These last-mentioned olefins in particular can, in liquefied or liquid state, also form the solvent in the polymerization or copolymerization reaction.
The metal complexes according to the invention in some cases have low polymerization activity, or none at all, and are then brought into contact with an activator, component (B), in order to develop good polymerization activity. Examples of suitable activator compounds are those of the aluminoxane type, in particular methylaluminoxane, MAO. Aluminoxanes are prepared, for example, by the controlled addition of water or water-containing substances to alkylaluminum compounds, in particular trimethylaluminum. Aluminoxane preparations which are suitable as cocatalyst are commercially available. It is assumed that this is a mixture of cyclic and linear compounds. The cyclic aluminoxanes can be summarized by the formula (R28AlO)s and the linear aluminoxanes by the formula R28(R28AlO)sAlR282, where s denotes the degree of oligomerization and is a number from about 1 to 50. Advantageous aluminoxanes essentially consist of aluminoxane oligomers having a degree of oligomerization of from about 1 to 30, and R28 is preferably a C1-C6-alkyl radical, particularly preferably methyl, ethyl, butyl or isobutyl.
Besides the aluminoxanes, other suitable activator components are those used in so-called cationic activation of metallocene complexes. Activator components of this type are disclosed, for example, in EP-B1-0468537 and EP-B1-0427697. In particular, these activator compounds (B) can be boranes, boroxines or borates, for example trialkylborane, triarylborane, trimethylboroxine, dimethylanilinium tetraarylborate, trityl tetraarylborate, dimethylanilinium boratabenzenes or trityl boratabenzenes (see WO-A-97/36937). Particular preference is given to boranes or borates carrying at least two perfluorinated aryl radicals. Particularly suitable activator compounds (B) are compounds from the group consisting of aluminoxane, dimethylanilinium tetrakispentafluorophenylborate, trityl tetrakispentafluorophenylborate or trispentafluorophenylborane.
It is also possible to employ activator compounds having stronger oxidizing properties, for example silver borates, in particular silver tetrakispentafluorophenylborate, or ferrocenium borates, in particular ferrocenium tetrakispentafluorophenylborate or ferrocenium tetraphenylborate.
The activator component may furthermore be compounds such as alkylaluminum compounds, in particular trimethylaluminum, triethylaluminum, triisobutylaluminum, tributylaluminum, dimethylaluminum chloride, dimethylaluminum fluoride, methylaluminum dichloride, methylaluminum sesquichloride, diethylaluminum chloride and aluminum trifluoride. It is also possible to employ the hydrolysis products of alkylaluminum compounds with alcohols (see, for example, WO-A-95/10546).
The activator compounds may furthermore also be alkyl compounds of lithium, magnesium or zinc, for example methylmagnesium chloride, methylmagnesium bromide, ethylmagnesium chloride, ethylmagnesium bromide, butylmagnesium chloride, dimethylmagnesium, diethylmagnesium, dibutylmagnesium, methyllithium, ethyllithium, methylzinc chloride, dimethylzinc or diethyl zinc.
It is sometimes desirable to use a combination of various activators. This is known, for example, in the case of metallocenes, where boranes, boroxines (WO-A-93/16116) and borates are frequently employed in combination with an alkylaluminum compound. In general, a combination of various activator components with the transition-metal complex according to the invention is also possible.
The amount of activator compounds to be used depends on the type of activator. In general, the molar ratio between the metal complex (A) and the activator compound (B) can be from 1:0.1 to 1:10,000, preferably from 1:1 to 1:2000. The molar ratio between the metal complex (A) and dimethylanilinium tetrakispentafluorophenylborate, trityl tetrakispentafluorophenylborate or trispentafluorophenylborane is from 1:1 to 1:20, preferably from 1:1 to 1:15, particularly preferably from 1:1 to 1:5, and that between the metal complex (A) and methylaluminoxane is preferably from 1:1 to 1:2000, particularly preferably from 1:10 to 1:1000. Since many of the activators, for example alkylaluminum compounds, are simultaneously used to remove catalyst poisons (so-called scavengers), the amount employed depends on the contamination of the other starting materials. However, the person skilled in the art can determine the optimum amount by simple trials.
The transition-metal complex can be brought into contact with the activator compound(s) either before or after contacting with the olefins to be polymerized. Preactivation with one or more activator compounds before mixing with the olefin and further addition of the same or another activator compounds after contacting of this mixture with the olefin is also possible. Preactivation is generally carried out at temperatures of from 10 to 100xc2x0 C., preferably from 20 to 80xc2x0 C.
It is also possible for more than one of the transition-metal complexes according to the invention to be brought into contact simultaneously with the olefin to be polymerized. This has the advantage that a further range of polymers can be produced. In this way, bimodal products, for example, can be prepared.
Another broad product range can be achieved by using the complexes according to the invention in combination with at least one conventional olefin-polymerization catalyst (C). Particularly suitable catalysts (C) here are classical Ziegler-Natta catalysts based on titanium, classical Phillips catalysts based on chromium oxides, metallocenes, so-called constrained geometry complexes (see, for example, EP-A-0416815 or EP-A-0420436), nickel and palladium bisimine systems (for their preparation, see WO-A-98/03559), iron and cobalt pyridinebisimine compounds (for their preparation, see WO-A-98/27124) or chromium amides (see, for example, JP-95/170947) Thus, such combinations also allow, for example, the preparation of bimodal products or the in-situ generation of comonomers. in this case, at least one transition-metal complex (A) is preferably used in the presence of at least one conventional olefin-polymerization catalyst (C) and, if desired, one or more activator compounds (B). Depending on the catalyst combinations (A and C), one or more activators are advantageous here. The polymerization catalysts (C) may also be supported and be used simultaneously or in any desired sequence with the complex (A) according to the invention.
The catalysts (A) according to the invention may, if desired, also be immobilized on an organic or inorganic support and used in the polymerization in supported form. This is a common method of avoiding reactor deposits and controlling the polymer morphology. Preferred support materials are silica gel, magnesium chloride, aluminum oxide, mesoporous materials, aluminosilicates and organic polymers, such as polyethylene, polypropylene or polystryene, in particular silica gel or magnesium chloride.
The activator compounds (B) and the metal complex (A) can be brought into contact with the support in various sequences or simultaneously. This is generally carried out in an inert solvent, which can be filtered off or evaporated after the immobilization. However, it is also possible to use the supported catalyst while still moist. Thus, the mixing of the support with the activator compound(s) or the contacting of the support with the polymerization catalyst can be carried out first. Preactivation of the catalyst with one or more activator compounds before mixing with the support is also possible. The amount of metal complex (A) (in mmol) per gram of support material can vary greatly, for example between 0.001 and 1. The preferred amount of metal complex (A) per gram of support material is from 0.001 to 0.5 mmol/g, particularly preferably from 0.005 to 0.1 mmol/g. in a possible embodiment, the metal complex (A) can also be prepared in the presence of the support material. Another type of immobilization is prepolymerization of the catalyst system with or without prior supporting.
The process according to the invention allows the preparation of olefin polymers. The term polymerization, as used here to describe the invention, covers both polymerization and oligomerization, i.e. oligomers and polymers having molecular weights in the range from about 56 to 4,000,000 can be produced by this process.
Owing to their good mechanical properties, the olefin polymers and copolymers prepared using the complexes according to the invention are particularly suitable for the production of films, fibers and moldings. This applies both to the polymers and copolymers obtained using one or more of the substituted monocyclopentadienyl, monoindenyl, monofluorenyl or heterocyclopentadienyl complexes of chromium, molybdenum or tungsten according to the invention and to the combinations thereof with one or more of the conventional olefin-polymerization catalysts (C).
The catalysts according to the invention have very good productivities. If the results from DE-A-19710615 are compared, better (pressure-averaged) activities are found, in particular under industrially relevant polymerization conditions (polymerization time of one hour).
Unexpectedly, the complexes according to the invention are also distinguished by good thermal stability. For example, they can be refluxed for a period of several hours in toluene without decomposing.
The examples below illustrate the invention:
All work was, unless stated otherwise, carried out in the absence of air and moisture. Toluene and THF were dried and distilled over a molecular-sieve column or sodium/benzophenone. Triisobutylaluminum (2 M in heptane) was obtained from Witco, MAO (methylaluminoxane 10% in toluene) and N,Nxe2x80x2-dimethylanilinium tetrakis(pentafluorophenyl)borate from Albemarle, and MAO (methylaluminoxane 30% in toluene) from Witco GmbH.
The starting compounds shown below were prepared by the literature methods cited:
8-Bromoquinoline
a) J. Mirek, Roczniki Chem. 1960, 34, 1599-1606;
b) E. Reimann in Houben-Weyl, Methoden der Organischen Chemie, 4th Edn., Volume E7a, 366
8-Bromo-2-methylquinoline: C. M. Leir, J. Org. Chem. 1977, 42, 911-913
2,3,4,5-Tetramethylcyclopent-2-enone: F. X. Kohl, P. Jutzi, J. Organomet. Chem. 1983, 243, 119-121
2,3-Dimethylcyclopent-2-enone
a) M. Dorsch, V. Jxc3xa4ger, W. Spxc3x6nlein, Angew. Chem. 1984, 96, 815-16; Angew. Chem., Int. Ed. Engl. 1984, 23, 798;
b) M. Dorsch, Dissertation, University of Wxc3xcrzburg, 1985
1-(8-Quinolyl)-2,3,4,5-tetramethylcyclopentadiene and 1-(8-quinolyl)-(2,3,4,5-tetramethyl)trimethylsilylcyclopentadiene: M. Enders, R. Rudolph, H. Pritzkow Chem. Ber. (1996), 129, 459-463.
Analysis
NMR samples were taken under an inert gas and sealed in if necessary. The internal standard used in the 1H- and 13C-NMR spectra were the solvent signals, whose chemical shifts were converted to TMS. NMR measurements were carried out using a Bruker AC 200 and, in particular COSY experiments, on a Bruker AC 300.
Mass spectra were measured on a VG Micromass 7070 H and a Finnigan MAT 8230. High-resolution mass spectra were measured on Jeol JMS-700 and VG ZAB 2F instruments.
Elemental analyses were carried out using a Heraeus CHNxe2x80x94O-Rapid.
The comonomer content of the polymer (%C6), its methyl side-chain content per 1000 carbon atoms in the polymer chain (CH3/1000) and its density were determined by IR spectroscopy.
The xcex7 value was determined using an automatic Ubbelohde viscometer (Lauda PVS 1) at 130xc2x0 C. using decalin as solvent (ISO 1628 at 130xc2x0 C., 0.001 g/nl of decalin).
The molecular weight distributions and the means Mn, Mw and Mw/Mn derived therefrom were determined by high-temperature gel permeation chromatography in accordance with DIN 55672 under the following conditions: solvent: 1,2,4-trichlorobenzene, flow rate: 1 ml/min, temperature: 140xc2x0 C., calibration with PE standards.
Abbreviations used
General Synthetic Procedure
Ligand Synthesis
An equimolar amount of n-BuLi was added to 8-bromoquinoline or N,N-dimethylaniline, and the mixture was subsequently reacted with tetramethylcyclopentenone or 1-indanone. After hydrolysis and acid-catalyzed elimination of water, the corresponding ligand was isolated (yields between 40 and 70%).
Complex Synthesis
The ligand anions were prepared by deprotonation using n-BuLi or potassium hydride and reacted with the corresponding metal halide. Purification was carried out by reprecipitation or recrystallization (yields generally about 60%).